RRM1 maintains centrosomal integrity via CHK1 and CDK1 signaling during replication stress.

DNA lesion-induced centrosomal abnormalities during the replication phase are relatively unknown. Here, we report that RNAi-mediated depletion of RRM1 induces cell-cycle arrest at the replication phase, along with severe DNA damage and centrosomal amplification. Interestingly, CHK1 depletion synergistically increased RRM1-depletion-induced centrosomal amplification. In response to hydroxyurea, CHK1 was delocalized from the centrosome by RRM1 depletion. Moreover, CDK1, which functions in centrosome separation and is inhibited by CHK1, was found to be essential for RRMI1-depletion-induced centrosomal amplification. Thus, we herein demonstrate that RRM1 preserves chromosomal stability via the CHK1- and CDK1-dependent stabilization of the centrosomal integrity at the replication stage.